10216721 has 4 divisors (see below), whose sum is σ = 10246512. Its totient is φ = 10186932.

The previous prime is 10216709. The next prime is 10216727. The reversal of 10216721 is 12761201.

10216721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-10216721 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 10216693 and 10216702.

It is not an unprimeable number, because it can be changed into a prime (10216727) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14375 + ... + 15068.

It is an arithmetic number, because the mean of its divisors is an integer number (2561628).

Almost surely, 2^10216721 is an apocalyptic number.

It is an amenable number.

10216721 is a deficient number, since it is larger than the sum of its proper divisors (29791).

10216721 is an equidigital number, since it uses as much as digits as its factorization.

10216721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29790.

The product of its (nonzero) digits is 168, while the sum is 20.

The square root of 10216721 is about 3196.3605866673. The cubic root of 10216721 is about 216.9887299746.

Adding to 10216721 its reverse (12761201), we get a palindrome (22977922).

The spelling of 10216721 in words is "ten million, two hundred sixteen thousand, seven hundred twenty-one".